图3. 青藏高原高寒草地环境因子对土壤酶活性影响的冗余分析(RDA)。AD1-AD3表示高寒荒漠3个样点; ADS1-ADS5表示高寒荒漠草原5个样点; AM1-AM5表示高寒草甸5个样点; AMS1- AMS3表示高寒草甸草原3个样点; AS1-AS5表示高寒草原5个样点。Act, 放线菌; APB, 地上植物生物量; APOM, 地上植物有机质; APTN, 地上植物总氮; C:N、C:P、N:P分别为土壤碳氮磷含量之比; G+, 革兰氏阳性细菌; G-, 革兰氏阴性细菌; ρb, 容重; SOM, 土壤有机质; TN, 总氮; TP, 总磷; UPB, 地下植物生物量; UPOM, 地下植物有机质; UPTN, 地下植物总氮。酶简写同表1。

Fig. 3. Redundancy analysis (RDA) of the effects of environmental factors on soil enzyme activity in alpine grasslands on the Qingzang Plateau. AD1-AD3 represent three samples of alpine desert; ADS1-ADS5 represent five samples of alpine desert steppe; AM1- AM5 represent five samples of alpine meadow; AMS1-AMS3 represent three samples of alpine meadow steppe; AS1-AS5 represent five samples of alpine steppe. Act, actinomycetes; APB, above-ground plant biomass; APOM, above-ground plant organic matter; APTN, above-ground plant total nitrogen; C:N, C:P, N:P represent the ratio between carbon、nitrogen and phosphorus; G+, gram-positive bacteria; G-, gram-negative bacteria; ρb, bulk density; SOM, soil organic matter; TN, total nitrogen; TP, total phosphorus; UPB, below-ground plant biomass; UPOM, below-ground plant organic matter; UPTN, below-ground plant total nitrogen. Abbreviations for enzymes are shown in Table 1.